滑块决定重力

Question

到目前为止，我已经创建了一个矩形，从底部开始向上移动使用UiDynamicAnimator。我希望用户确定负重力的"强度"。我希望用户通过滑块来确定这个值。

这是我到目前为止的代码:

    import UIKit
class ViewController: UIViewController {
    var orangeSquare: UIView?
    var animator: UIDynamicAnimator?
    override func viewDidLoad() {
        super.viewDidLoad()

        func sliderChanged(sender: AnyObject) {
            var sliderValue = sender.value
        }
                //Create animation
            let dim = CGRectMake(100, 500, 200, 100)
            orangeSquare = UIView(frame: dim)
            orangeSquare?.backgroundColor = UIColor.orangeColor()
                //Add item to the screen
            self.view.addSubview(orangeSquare!)
                //Initialize the animator
            animator = UIDynamicAnimator(referenceView: self.view)
                //Add gravity
            let gravity = UIGravityBehavior(items: [orangeSquare!])
            let direction = CGVectorMake(0.0, sliderValue)
            gravity.gravityDirection = direction
                //Collision
            let boundries = UICollisionBehavior(items: [orangeSquare!])
            boundries.translatesReferenceBoundsIntoBoundary = true
                //Add animations
            animator?.addBehavior(boundries)
            animator?.addBehavior(gravity)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

我得到两个错误:

"歧义使用' value ' "one_answers"使用未解析的标识符' sliderValue ' "

如何将' sliderValue '转换为只有一个小数点的浮点数?

Answer 1

您的代码缺少一些东西。sliderValue是一个无法解析的标识符，因为你只在sliderChanged中声明了它，但在viewDidLoad的主体中引用了它。此外，我认为你对value的使用是模棱两可的，因为你已经将函数的参数声明为AnyObject，其值可以是许多东西中的任何一个!

你的代码缺少将滑块值的变化与重力行为的变化联系起来的机制。因此，我使用附加到滑块对象的显式目标来实现这一点。我还加了一个标签来表示重力的大小。这是相当粗糙，但我认为它达到了你想要做的。

import UIKit
class ViewController: UIViewController {
    var dynamicAnimator : UIDynamicAnimator!
    var gravityBehaviour : UIGravityBehavior!
    var orangeSquare : UIView!
    var slider : UISlider!
    var sliderLabel : UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Subviews
        self.orangeSquare = {
            let oS : UIView = UIView(frame: CGRect(origin: CGPoint(x: (self.view.frame.width / 2) - 100, y: 500), size: CGSize(width: 200, height: 200)))
            oS.backgroundColor = UIColor.orange
            return oS
        }()
        self.slider = UISlider(frame: CGRect(origin: CGPoint(x: 100, y: 100), size: CGSize(width: self.view.frame.width - 400, height: 50)))
        self.slider.addTarget(self, action: #selector(self.sliderValueDidChange), for: UIControlEvents.allTouchEvents)
        self.slider.minimumValue = -5
        self.slider.maximumValue = 5
        self.slider.value = 0
        self.sliderLabel = UILabel(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 100), size: CGSize(width : 50, height: 50)))
        self.sliderLabel.backgroundColor = UIColor.red
        self.sliderLabel.textAlignment = NSTextAlignment.center
        self.sliderLabel.textColor = UIColor.white
        self.sliderLabel.text = String(self.slider.value)
        // Assemble
        self.view.addSubview(self.orangeSquare)
        self.view.addSubview(self.slider)
        self.view.addSubview(self.sliderLabel)
        // Configure dynamic behaviours
        self.dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
        self.gravityBehaviour = UIGravityBehavior(items: [self.orangeSquare])
        self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: 0)
        // Configure boundaries
        let boundaries : UICollisionBehavior = UICollisionBehavior(items: [self.orangeSquare])
        boundaries.translatesReferenceBoundsIntoBoundary = true
        self.dynamicAnimator.addBehavior(self.gravityBehaviour)
        self.dynamicAnimator.addBehavior(boundaries)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    func sliderValueDidChange() {
        // When the slider value changes, update the label text and the gravity vector
        self.sliderLabel.text = String((round(self.slider.value) * 10) / 10)
        self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: CGFloat(-1 * self.slider.value))
    }
}

希望有帮助。所有最好的!

Answer 2

import UIKit
class ViewController: UIViewController {
    var dynamicAnimator : UIDynamicAnimator!
    var gravityBehaviour : UIGravityBehavior!
    var orangeSquare : UIView!
    var slider : UISlider!
    var sliderLabel : UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Subviews
        self.orangeSquare = {
            let oS : UIView = UIView(frame: CGRect(origin: CGPoint(x: (self.view.frame.width / 2) - 100, y: 500), size: CGSize(width: 200, height: 200)))
            oS.backgroundColor = UIColor.orangeColor()
            return oS
            }()
        self.slider = UISlider(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 100), size: CGSize(width: self.view.frame.width - 300, height: 150)))
        self.slider.addTarget(self, action: #selector(self.sliderValueDidChange), forControlEvents: UIControlEvents.AllTouchEvents)
        self.slider.minimumValue = -10
        self.slider.maximumValue = 10
        self.slider.value = 0
        self.sliderLabel = UILabel(frame: CGRect(origin: CGPoint(x: self.view.frame.width - 100, y: 200), size: CGSize(width : 50, height: 50)))
        self.sliderLabel.backgroundColor = UIColor.redColor()
        self.sliderLabel.textAlignment = NSTextAlignment.Center
        self.sliderLabel.textColor = UIColor.whiteColor()
        self.sliderLabel.text = String(self.slider.value)
        // Assemble
        self.view.addSubview(self.orangeSquare)
        self.view.addSubview(self.slider)
        self.view.addSubview(self.sliderLabel)
        // Configure dynamic behaviours
        self.dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
        self.gravityBehaviour = UIGravityBehavior(items: [self.orangeSquare])
        self.gravityBehaviour.gravityDirection = CGVector(dx: 0.0, dy: 0.0)
        // Configure boundaries
        let boundaries : UICollisionBehavior = UICollisionBehavior(items: [self.orangeSquare])
        boundaries.translatesReferenceBoundsIntoBoundary = true
        self.dynamicAnimator.addBehavior(self.gravityBehaviour)
        self.dynamicAnimator.addBehavior(boundaries)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    func sliderValueDidChange() {
        // When the slider value changes, update the label text and the gravity vector
        self.sliderLabel.text = String((round(self.slider.value) * 10) / 10)
        self.gravityBehaviour.gravityDirection = CGVector(dx: 0, dy: CGFloat(-1 * self.slider.value))
    }
}